I need to be able to walk someone through a 3d model in real time
Walking through real time, with near-render quality, would be possible with eevee rendering engine added with blender 2.8. Depending on your computer, this might be enough.

More viable way would be model everything in blender, export it to a gaming engine - Unity for instance. Unity has a pre-made scrips that will not require you to program, to enable basic walk functionality, however it will take some work to move project between Blender and Unity, depending on how complex it is (screenshot would be helpful for better estimate).

If I was you, I would model the entire scene, including materials while making sure my objects have uvmapping configured. I would then bake all the textures for every object to keep as much information as possible.

After that, I would re-create the scene in Unity by importing objects, applying textures and re-creating materials (materials do not move between modeling software and game engines, they are almost always exclusive to only one software and whenever you move something you have to re-create it). Unity has different material capabilities than blender so it will probably be impossible to make it 100% identical, but with baking (which enables you to save a lot of info as textures - stuff like shadows, ambient occlusion, emission, colours, lotsa stuff) it should be relatively close.

Using game engine has a added benefit of being able to generate the application that client can take home - it can be exe file, phone app (with a bit of work) or even a webapp.

Skillset you'd need would require: Modeling, UVMapping, Baking, basic Unity3d usage.